Correlation between mean transfer momentum and multiplicity of charged particles in pp and ppbar collisions: from ISR to LHC

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Correlation between mean transfer momentum and
multiplicity of charged particles in pp and ppbar
collisions from ISR to LHC
Report by G.Feofilov, II Russian-Spain Congress,
02-04 Oct.,St.Petersburg
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Ouitline

• Some motivations for pt-Nch correlation
• Experiment
• Effective pomeron exchange model (EPEM)
• EPEM modifications
• Results

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Charged Particle ltpTgt vs.Multiplicity ALICE
arXiv1307.1094 from pp collisions ? to p-Pb and
? to Pb-Pb
In narrow ?? window at midrapidity
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Some pre-History
In 1980 we found that the decay temperature
of a fire-ball is of the order of a pion
rest-energy, mpc2, much smaller than the
participating energies in the collision

• Cosmic rays data

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UA1 Collab., G. Arnison et al., Phys. Lett. 118B
(1982)167.
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Experimentally Observed pt-Nch correlations in pp
and ppbar collisions
NA49 collab. arXivhep-ex/0311009. ABCDHW
Collaboration, Phys. Lett. 132B (1983) 463. UA1
collab., Nucl Phys 335B (1990) 261. F.Abe et.al,
Phys.Rev.Lett. 61 (1988) 1819. C.De Marzo et al.
Phys. Rev. 29D (1984) 363. V.V. Aivazyan et al.,
Phys.Lett. 209B (1988) 103. T. Alexopoulos et
al., Phys. Lett. 336B (1994) 599.
Compilation of data in N. Armesto, D. Derkah,
and G. A. Feofilov "ltptgt- multiplicity
correlations in a Multi- Pomeron exchange model
with string collective effects" , Yad.Fyz., 2008,
v71, No12, pp.1-10
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Features of pt-Nch Correlations in pp and ppbar
collisions.

• ltptgtNch does not grow with energy at low Nch.
• ltptgtNch flattens at high Nch.
• .
• Experiments on pt-Nch correlations can be divided
  into two groups depending on the value of ltptgt at
  Nch close to 0... (??? see further)

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Classical Multi-Pomeron Exchange Model
(Regge-Gribov approach)
Pomeron is a virtual particle that is exchanged
during the inelastic scatering process with
vacuum quantum numbers flow.
It can be considered as a pair of strings.
The number of pomerons exchanged rises with
energy.
Collective effects are not included in the model.
A.Capella, U.P.Sukhatme, C.-I.Tan and J.Tran
Thanh Van, Phys. Rep.236(1994)225
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Classical Multi-Pomeron Exchange Model
distribution of Nch over pT
normalized cross section of simultaneous
production of n-pomeron showers
probability for strings to give
particles after hadronization
transverse momentum distribution for particles
coming from a single string

1. B. Kaidalov, K. A. Ter-Martirosyan Phys. Lett.
   11B (1982) 247

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Classical Multi-Pomeron Exchange Model
distribution of Nch over pT
normalized cross section of simultaneous
production of n-pomeron showers
probability for strings to give
particles after hadronization
transverse momentum distribution for particles
coming from a single string

1. B. Kaidalov, K. A. Ter-Martirosyan Phys. Lett.
   11B (1982) 247

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Classical Multi-Pomeron Exchange Model
distribution of Nch over pT
normalized cross section of simultaneous
production of n-pomeron showers
probability for strings to give
particles after hadronization
transverse momentum distribution for particles
coming from a single string

1. B. Kaidalov, K. A. Ter-Martirosyan Phys. Lett.
   11B (1982) 247

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EPEM Modifications
reported by V.Kovalenko at QFTHEP'2013, Repino,
Saint Petersburg, Russia
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Parameters
Classical model parameters
t average string tension
k mean number of particles produced per unit
rapidity by one string
Modificated model parameter b
- efficient string collective coefficient
N. Armesto, D. Derkah, and G. A. Feofilov ,
Yad.Fyz., 2008, v71, No12, pp.1-10
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Theoretical Motivation Color string formation
and decay

• 2-stage scenario of color string formation
• and decay
• A.Capella, U.P.Sukhatme, C.--I.Tan
• and J.Tran Thanh Van,
• Phys. Lett. B81 (1979) 68 Phys. Rep.,236(1994)
  225.
• A.B.Kaidalov K.A.Ter-Martirosyan ,
• Phys.Lett., 117B(1982)247.
• Do these color strings interact
  and what is the signal?
• Abramovskii V. A., Gedalin E. V., Gurvich E. G.,
  Kancheli O. V. ,
• JETP Lett., vol.47, 337-339 , 1988 .
• Color string fusion phenomenon
• M.A.Braun and C.Pajares,
• Phys. Lett. \bf B287 (1992) 154\\ Nucl. Phys.
  \bf B390 (1993) 542, 549

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Conclusions

• Experirmental results on mean pt and on pt-n
  correlation are summarized in a wide energy
  range.
• 2-parameter Multi-Pomeron exchange model is
  developed.
• Negative and positive pT-Nch correlations in pp
  and ppbar collisions are reproduced in one
  approach of modified multi-Pomeron exchange
  model.
• Smooth behavior of parameter (responsible
  for string fusion) ) with energy is observed.
• Results on pT-Nch correlation analysis are in
  agreement with string fusion model hypothesis
• .

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Back-up slides
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Mean number (black line ____ ) and dispersion
(dots .) in number of Pomerons vs. energy
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Fit results
N. Armesto, D. Derkah, and G. A. Feofilov ,
Yad.Fyz., 2008, v71, No12, pp.1-10
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Fit results
N. Armesto, D. Derkah, and G. A. Feofilov ,
Yad.Fyz., 2008, v71, No12, pp.1-10
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Dispersion in number of pomerons
N. Armesto, D. Derkah, and G. A. Feofilov ,
Yad.Fyz., 2008, v71, No12, pp.1-10
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C.M.G. LATTES, Y. FUJIMOTO and S.
HASEGAWAPHYSICS REPORTS 65, No. 3(1980) 151-229.

• we found that the decay temperature of a
  fire-ball is of the order of a pion rest-energy,
  mpc2, much smaller than the participating
  energies in the collision. It came from the
  observation that the majority of produced
  particles in a jet are pions, heavier kaons and
  nucleons being few, and that their transverse
  momentum, Pt, is as small as a few hundreds of
  MeV/c. Thus, it was almost clear to us that a
  fire-ball an intermediate product is produced
  in the collision and then it decays into a
  cluster of hadrons with substantially longer
  life-time than the characteristic collision time

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Charged Particle ltpTgt vs.Multiplicity ALICE
arXiv1307.1094from pp collisions ? to p-Pb and
? to Pb-Pb
pp collisions, narrow Dh window
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Dual Parton Model calculations
In this model an additional assumption was made
a transverse momentum of sea quarks was
introduced as a parameter. This parameter was
fitted to be 1.1 GeV.
P. Aurenche, F. W. Bopp and J. Ranft, Phys.
Lett. 147B, (1984) 212